Automatic drug delivery devices

Abstract

The invention provides in one aspect a drug delivery device comprising a drug container (16), and a plunger (18) positioned within the container assembly, the drug container assembly having an outlet for dispensing the drug, wherein, in an initial position, the outlet is sealed; a drive mechanism comprising a first stored energy source (42) operable to apply pressure on the plunger or the drug container to pressurize the drug, and a first release mechanism operable to unseal the outlet after the drug has been pressurized. In another aspect, there is provided a drug delivery device comprising a housing, including an external housing portion configured to be held in use and a drug containing portion containing a drug, a needle assembly comprising a needle fixed to a needle hub, the needle hub configured to move relative to the drug containing portion from an initial position within the housing to an insertion position in which the needle extends beyond the housing, a first stored energy source configured to move the needle hub from the initial position to the insertion position, and a plunger within the housing and configured to move relative to the drug containing portion to eject the drug through the needle when the needle is in the insertion position.

The invention claimed is: 
     
       1. A drug delivery device for use at an injection site, the drug delivery device comprising:
 a drug container assembly containing a drug, and a plunger positioned within the drug container assembly, the drug container assembly having an outlet for dispensing the drug; 
 a drive mechanism comprising a first stored energy source operable to apply pressure on the plunger or the drug container assembly to pressurise the drug; 
 a hypodermic needle through which the drug is delivered in use, the hypodermic needle having a distal needle end and a proximal needle end; 
 a needle insertion mechanism configured to move the hypodermic needle proximally relative to the drug container assembly to insert the proximal needle end of the hypodermic needle automatically into the injection site, wherein the device is configured such that a hydraulic pressure of the drug, provided by the first stored energy source, is used to move the needle insertion mechanism; and 
 a first release mechanism operable to unseal the outlet after the drug has been pressurized, 
 wherein the drive mechanism forms a first sub-assembly, and the drug container assembly and the first release mechanism form a second sub-assembly separate to the first sub-assembly, wherein the device is configured such that energy is stored within the first stored energy source as a result of the first sub-assembly being connected to the second sub-assembly. 
 
     
     
       2. The drug delivery device according to  claim 1 , wherein the first release mechanism operates to displace a needle hub relative to the drug container assembly to unseal the outlet. 
     
     
       3. The drug delivery device according to  claim 1 , wherein the hypodermic needle is provided in a needle hub in an initial position, sealing the outlet, wherein the needle hub is restrained from proximal movement by a locking element, wherein the first release mechanism is operable to release the needle hub from the locking element so that it can be driven by the pressure of the drug in a proximal direction and wherein the needle hub is configured such that movement of the needle hub in the proximal direction from the initial position to an insertion position unseals the outlet, allowing the drug to pass from the drug container assembly through the needle to the injection site. 
     
     
       4. The drug delivery device according to  claim 1 , further comprising a second release mechanism operable to release the first stored energy source or store energy within the first stored energy source to pressurise the drug, wherein the second release mechanism is operated by removing a cap, cover or package from the device. 
     
     
       5. The drug delivery device according to  claim 1 , wherein the first stored energy source is a compression spring that is compressed as the first sub-assembly is connected to the second sub-assembly. 
     
     
       6. The drug delivery device according to  claim 1 , wherein the first sub-assembly is connected to the second sub-assembly by a screw fitting or a mechanical interlock fitting. 
     
     
       7. The drug delivery device according to  claim 1 , wherein the first sub-assembly is configured to be disconnected from the second sub-assembly so as to be re-usable with a different second sub-assembly. 
     
     
       8. The drug delivery device according to  claim 1 , wherein the first release mechanism operates to open a valve that seals the outlet. 
     
     
       9. The drug delivery device according to  claim 1 , further comprising a main housing, which may be part of or separate to the drug container assembly, and a skin contact element, the skin contact element forming a front end of the device, movement of the skin contact element relative to the main housing from an initial position to an insertion position operating or allowing the operation of the first release mechanism. 
     
     
       10. The drug delivery device according to  claim 9 , wherein the first release mechanism comprises a first locking surface on the skin contact element that in the initial position limits relative movement between a needle hub and the main housing or drug container assembly. 
     
     
       11. The drug delivery device according to  claim 1 , the needle insertion mechanism including a needle hub that seals the outlet of the drug container assembly when the needle hub is in an initial position, the hypodermic needle being fixed to the needle hub, the needle hub allowing the drug to pass into the distal needle end of the hypodermic needle and into the injection site when the needle hub is moved proximally from the initial position to an insertion position. 
     
     
       12. A drug delivery device comprising:
 a housing, including an external housing portion configured to be held in use and a drug containing portion containing a drug; 
 a needle assembly comprising a needle fixed to a needle hub, 
 the needle having a proximal end for insertion into a patient, 
 the needle hub configured to move proximally relative to the drug containing portion from an initial position within the housing to an insertion position, wherein in the insertion position the needle extends beyond the housing; 
 a plunger within the housing and configured to move relative to the drug containing portion to eject the drug through the needle when the needle is in the insertion position, and 
 a first stored energy source configured to provide a motive force for both moving the needle hub to the insertion position and moving the plunger relative to the drug containing portion to eject the drug through the needle; 
 the needle hub being configured to move proximally relative to the drug containing portion from the initial position to the insertion position in response to pressure from the drug acting on the needle hub, 
 wherein the needle has a distal end for receiving the drug, and wherein the device further comprises a sealing element fixed relative to the needle and configured to seal the drug containing portion when the needle hub is in the initial position, and 
 wherein the needle hub comprises an inlet portion positioned around the distal end of the needle, the inlet portion providing fluid communication between the drug containing portion and the distal end of the needle when the needle hub is in the insertion position. 
 
     
     
       13. The drug delivery device according to  claim 12 , wherein the housing comprises a skin contact element, the skin contact element being movable relative to the external housing portion to release the first stored energy source. 
     
     
       14. The drug delivery device according to  claim 12 , further comprising a sealing element fixed to the drug containing portion and positioned around a shaft of the needle, the sealing element maintaining a fluid tight seal around the shaft of the needle as the needle hub moves from the initial position to the insertion position. 
     
     
       15. A drug delivery device for use at an injection site, the drug delivery device comprising:
 a drug container assembly containing a drug, and a plunger positioned within the drug container assembly, the drug container assembly having an outlet for dispensing the drug, wherein, in an initial position, the outlet is sealed; 
 a drive mechanism comprising a first stored energy source operable to apply pressure on the plunger or the drug container assembly to pressurise the drug; and 
 a first release mechanism operable to unseal the outlet after the drug has been pressurised, 
 wherein the drive mechanism forms a first sub-assembly, and the drug container assembly and first release mechanism form a second sub-assembly separate to the first sub-assembly, wherein the device is configured such that energy is stored within the first stored energy source as the first sub-assembly is connected to the second sub-assembly. 
 
     
     
       16. The drug delivery device according to  claim 15 , wherein the first stored energy source is a compression spring that is compressed as the first sub-assembly is connected to the second sub-assembly. 
     
     
       17. The drug delivery device according to  claim 15 , wherein the first sub-assembly is connected to the second sub-assembly by a screw fitting or a mechanical interlock fitting. 
     
     
       18. The drug delivery device according to  claim 15 , wherein the first sub-assembly is configured to be disconnected from the second subassembly so as to be re-usable with a different second sub-assembly. 
     
     
       19. The drug delivery device according to  claim 15 , comprising a hypodermic needle through which the drug is delivered in use, and a needle insertion mechanism configured to move the hypodermic needle relative to the drug container assembly to insert the hypodermic needle automatically into the injection site, wherein operation of the first release mechanism releases the needle insertion mechanism and unseals the outlet. 
     
     
       20. A drug delivery device for use at an injection site, the drug delivery device comprising:
 a drug container assembly containing a drug, and a plunger positioned within the drug container assembly, the drug container assembly having an outlet for dispensing the drug; 
 a drive mechanism comprising a compression spring operable to apply pressure on the plunger or the drug container assembly to pressurise the drug; and 
 a first sealing member secured to the drug container assembly and sealing the outlet of the drug container assembly; 
 a hypodermic needle through which the drug is delivered in use, the hypodermic needle extending through the first sealing member when the hypodermic needle is in an initial position so that a seal is maintained between the hypodermic needle and the first sealing member, the hypodermic needle having a distal needle end and a proximal needle end, the hypodermic needle being positioned proximally of the drug container assembly, 
 a second sealing member sealing the distal needle end of the hypodermic needle when the hypodermic needle is in the initial position, the second sealing member allowing the drug to pass the second sealing member to flood a space between the first sealing member and the second sealing member; 
 an insertion mechanism operable to move the hypodermic needle proximally from the initial position to an insertion position so that the hypodermic needle disengages the second sealing member to allow the drug to enter the distal needle end of the hypodermic needle to pass to the injection site, 
 wherein the drive mechanism forms a first sub-assembly, and the drug container assembly and the insertion mechanism form a second sub-assembly separate to the first sub-assembly, wherein the drug delivery device is configured such that energy is stored within the compression spring as the first sub-assembly is connected to the second sub-assembly. 
 
     
     
       21. A drug delivery device for use at an injection site, the drug delivery device comprising:
 a drug container assembly containing a drug, and a plunger positioned within the drug container assembly, the drug container assembly having an outlet for dispensing the drug; 
 a drive mechanism comprising a first stored energy source operable to apply pressure on the plunger or the drug container assembly to pressurise the drug; 
 a hypodermic needle through which the drug is delivered in use, the hypodermic needle having a distal needle end and a proximal needle end; 
 a needle insertion mechanism configured to move the hypodermic needle proximally relative to the drug container assembly to insert the proximal needle end of the hypodermic needle automatically into the injection site, wherein the device is configured such that a hydraulic pressure of the drug, provided by the first stored energy source, is used to move the needle insertion mechanism; and 
 a first release mechanism operable to unseal the outlet after the drug has been pressurized, 
 the needle insertion mechanism including a needle hub that seals the outlet of the drug container assembly when the needle hub is in an initial position, the hypodermic needle being fixed to the needle hub, the needle hub allowing the drug to pass into the distal needle end of the hypodermic needle and into the injection site when the needle hub is moved proximally from the initial position to an insertion position.